All the Perl that's Practical to Extract and Report

Navigation

The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Without JavaScript enabled, you might want to
use the classic discussion system instead. If you login, you can remember this preference.

The CheckingAccount::withdraw method is actually "before" method advice. It will run that sub before running the superclass code (BankAccount). So what happens is that if there is not enough money in the account to cover the withdrawl, it will withdraw money from an account designated as the "overdraft account" to compensate.

The method "advice" feature, is something found in CLOS and some AOP systems. This example is actually taken directly from the book Practical Common Lisp [gigamonkeys.com] (scroll down to the section